The present invention relates generally to power machine tools and more particularly to a power tool jig capable of storing various predetermined stop positions to reproducibly and accurately position a work piece on a power tool. The jig is programmable to store multiple stop positions required for an entire project and is transferable to a variety of different power machine tools.
Precision woodworking, for example, cabinet making, often utilizes several different power tools for each project, requiring setting up each power tool and changing stop positions for a given work piece. For both the professional cabinet-maker and the home craftsman this can be a time consuming and expensive annoyance.
Woodworking operations require precise measurements for the cutting of wood stock to insure proper fit of assembled pieces. To insure proper fit, positioning jigs are used to position the work piece relative to a power tool cutting surface. Current practice utilizes positioning jigs for a wide variety of power tools such as a table saw, router table and drill press.
Although the advent of power machine tools has made woodworking both more efficient and easier, many of the techniques used today are virtually identical to techniques used centuries ago. However, positioning processes and devices used to determine the stop position for a cutting operation on the work piece are still evolving.
One such device used to position a work piece on a power machine tool is a fence, most commonly used on a table saw or router. Typically, the operator feeds the work piece by hand through the cutting tool by sliding one edge of the work piece along the fence, optionally, until the work piece contacts a stop block. The optional stop block located a predetermined distance from the cutting tool, placed to prevent further machining of the work piece.
Both the fence and optional stop block must be positioned to a new location each time a work piece cut is made to a different predetermined criteria. For this reason, multiple work pieces of identical shape are generally cut at the predetermined fence and optional stop block position prior to moving the fence and/or stop. Once the fence and/or optional stop has been moved, the fence and/or optional stop must be reset to a prior position to duplicate a previously cut piece. It is difficult and time consuming to accurately reposition the fence and optional stop in the original position, often resulting in inaccuracies in the final fit of the work pieces.
One shortcoming of the current practice of positioning devices is that they are typically made of heavy steel and permanently mounted to each woodworking power tool. Thus, they are quite cumbersome and time consuming to remove and reinstall. Additionally, it is quite expensive to equip each power tool with its own stop block and guide.
Accurate placement of each work piece cut is dependent upon the operator""s experience and skill. This is particularly important when cutting multiple work pieces of identical dimensions. One current method of aiding the operator in achieving this accurate cut placement is to mechanically position the fence through the use of a lead screw and a rotating knob. The rotating knob turns the lead screw, which augurs and positions the fence. The fence is adjusted prior to each cutting operation to a predetermined distance from the cutting tool according to the desired location of the cut. Typically, the operator feeds the work piece by hand through the cutting tool by sliding one edge of the work piece along the fence.
A wide range of positioning jigs have been designed in an attempt to improve the accuracy and reproducibility of the positioning process. For example, U.S. Pat. Nos. 4,793,604 and 5,716,045 include a fixed lower body member and a moveable upper body member. After the fence has been positioned, racks are meshed together by tightening a knob threaded through the middle of the upper and lower body members to prohibit further movement.
U.S. Pat. No. 5,215,296 discloses a positioning jig using a blade and a movable carriage mounted thereon. The carriage rides on tubular rails mounted to a base. Movement to a desired position is facilitated by two sets of rollers mounted to the carriage and contacting the top and bottom of the tubular rails.
Current practice positioning jigs have a single unit fixed measurement spacing and are limited in maximum measurement length. They must be repositioned after each change in desired work piece shape, with resultant inherent inaccuracy. Additional problems inherent in current practice positioning jigs are the inability to attach varied additional apparatus to the jig, and the limited capacity to accommodate work pieces of longer lengths. Current practice jigs are designed for a specific dedicated power machine tool, with limited cross tool interchangeability.
Accordingly, there remains a need for an inexpensive simple jig that is interchangeable with different power machine tools, able to accurately perform multiple operations, and capable of easily and accurately reproducing prior measurement settings while not being limited to a single unit of measurement.
The present invention provides a jig for reproducibly and accurately positioning a work piece on a power tool that is interchangeable with a variety of woodworking power tools. The invention has a built in memory that enables the user to make, program and store many, if not all, of the required stop positions used on the power tool to cut work pieces to required dimensions for a woodworking project.
Once the jig is installed on the appropriate power tool, a memory stick is slid to the desired position for that operation and the work piece is held against a fence for drilling, sawing, or routing, as needed. The jig comprises a primary fence having a first end, an opposing second end, a first side, an opposing second side and a top and opposing bottom, wherein the first and second sides are interposed between the first and second ends and the top and opposing bottom are supported by the first end, second end, first side and second side.
A universal memory stick is slidably attached to the primary fence, the memory stick having a first end, an opposing face end, a first side, an opposing second side and a top, wherein the first and second sides are interposed between the first and face ends and the top is supported by the first end, face end, first side and second side and includes a universal memory stick template. A follower assembly is mounted to the primary fence for maintaining a relative position of the primary fence to the universal memory stick.
One advantage of the present invention is that the jig is interchangeable with a variety of power tools. Because differing power tools may require their own positioning jig, the cost savings are multiplied by the number of power tools required for a given project.
Another advantage of the present invention is the ability to permanently store predetermined stop positions for duplication and use at a later time. In this manner, work pieces may be repeatedly cut to reproducibly precise dimensions, even after the jig has been repositioned. Because the stop positions are customized by the operator, the number of predetermined stops may range from an unlimited number to the exact amount required by a particular project.
Yet another advantage is the operator""s ability to alternate between varied units of incremental spacing. In this manner, the operator is not limited to a single measurement unit, as in current practice.
Still another advantage is the operator""s unlimited ability to increase the linear range of stop positions. In this manner, work pieces of infinite length may be easily and accurately measured.
Another advantage of the present invention is the ability to easily fasten other attachments, such as additional jigs and templates, a changeable zero clearance cut off block or the work piece to the jig for use with differing power tools, without disturbing any jig adjustments.
Another advantage of the present invention is the ability to easily compensate for varying power tool cutter widths.
Continuing and often interrelated improvements in processes and materials, such as the improvements of the present invention, can provide cost reductions and major increases in the performance of devices such as table saws, router tables, drill presses and other power woodworking tools.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.